Two-wheeled bogie for track-guided vehicles

ABSTRACT

A two-wheeled running gear for a track-guided vehicle comprising a running gear frame; a wheel carrier; first and second wheels coupled to opposite sides of the wheel carrier; first and second vertical pivot pins, the first vertical pivot pin coupled to the first side of the wheel carrier and movably connected to the first side of the running gear frame, the second vertical pivot pin coupled to the second side of the wheel carrier and movably connected to the second side of the running gear frame, the first and second wheels located between the first and second vertical pins; and means for controlling a movement of the first pivot pin relative to the running gear frame such that, during a curved track drive, the first pivot pin can be held substantially in place relative to the running gear frame while the second pivot pin can move relative to the running gear frame so that the line connecting the centers of the wheels is maintained substantially parallel to the radius of curvature of the track.

FIELD OF THE INVENTION

The invention relates to a two-wheeled running gear for track-guidedvehicles, having a traction-assisted means for steering and having awheel carrier.

BACKGROUND OF THE INVENTION

Since track-bound, and in particular rail-guided, vehicles forhigh-speed, regional and local transport have been equipped virtuallyexclusively with bogie-type running gears, so-called individual-wheelrunning gears have also recently become established. Whereas bogies havetwo or more sets of wheels or four or more so-called individual wheels,and are thus very heavy, individual-wheel running gears have twoindividual wheels, and individual-wheel-set running gears have one setof wheels.

In the case of track curves, bogies are steered by the leading set ofwheels or the leading individual wheels. The small axle spacing or wheelspacing means that the wheels travel through curves with only a smallamount of noise and low wear, and two or more bogies beneath thecarriage body provide for stable guidance along a rectilinear track atrelatively high speeds. Additional steering of the sets of wheels orindividual wheels in the bogie is achieved by the diagonal connectionbetween two sets of wheels or by utilizing the angular movements ofleading and trailing carriage bodies.

Two-wheeled individual-wheel running gears have become widespread, inparticular, in local and regional transport. Individual wheels make iteasier in design terms to provide for simple entrance into carriages byvirtue of the carriage floor being lowered to a level of approximately300 mm, which is the case in so-called low-floor vehicles. If theso-called rolling condition, which is characterized by virtuallyidentical rolling and circumferential speeds for the wheels which arerespectively on the inside and outside of the curve, and the so-calledadjustment condition, which describes the adjustment of the wheel planestangentially, or of the wheel axles radially, with respect to the rails,are maintained, there is a virtually physically ideal reduction in wearand noise, and thus a high degree of comfort. Various methods are usedin order to realize this ideal track guidance.

"Nahverkehrs-Praxis", no. 11/1992, p. 402 ff., discloses a three-partarticulated vehicle with, in each case, two individual-wheel runninggears per carriage body. Two individual wheels are arranged in one wheelcarrier and, for each carriage, two wheel carriers are mounted in therunning gear frame of the carriage body so as to be pivotable about thevertical pin in each case. The vertical king pin for the pivot pin islocated in the center between the wheels of the wheel carrier, in theplane of symmetry of the vehicle. The curve-dependent pivoting orsteering of the wheel carriers is effected by an additional steeringlinkage with respect to the pin-free articulation. In this case, thesteering linkage is moved in dependence on the articulation anglebetween the carriage bodies, and the articulation angle is adjusted in acurve-dependent manner, with the result that the wheel carriers can beadjusted approximately radially with respect to the curve. Similarpositively controlled steering of individual-wheel running gears, with,in each case, two individual wheels per running gear and a portal-likearticulated structure, was developed in Austria (cf. ZEV+DET Glas.Annalen 116 (1992) no. 8/9, p. 333 ff.).

An individual-wheel running gear with self-regulating individual wheelsis described in DE 34 09 103 A1 and DE 37 44 983 C2. Each of theindividual wheels can be steered about a dedicated vertical pivot pin.The individual-wheel carriers, which are located opposite one another onthe inside and outside of the curve, are connected by a track rod. Byway of the vertical pivot pins, which are located outside the stand-uppoints of the wheels, the forces produced during wheel/rail contact areutilized in order to guide the wheel planes back tangentially withrespect to the rail, with the result that the wear between wheel andrail is reduced considerably.

EP 02 95 462 B1 discloses an individual-wheel running gear structurewhich is equipped with actuating devices. Two individual wheels arearranged in a wheel carrier, and two wheel carriers are mounted in arunning gear frame so as to be pivotable about the vertical in eachcase. The king pin, which actually forms the vertical pivot pin, islocated in the centre between the wheels of a wheel carrier, in theplane of symmetry of the running gear frame. The curve-dependentpivoting of the wheel carriers is effected by one actuating device foreach wheel carrier. The actuating is supported on the running gear frameand, in dependence on an adjacent carriage body connected to thecarriage body in an articulated manner, pivots each wheel carrier aboutthe fixed pivot in the wheel-carrier center.

With curve control for individual wheels which is configured independence on the carriage-body articulation angle, the error in theadjustment which is correct for the curve increases as the articulationangle increases. Furthermore, it is not possible to achieve precisetangential positioning of the individual-wheel planes in the transitioncurve. The numerous articulations and connections of the steeringlinkage require a not inconsiderable amount of outlay for maintenanceand adjustment.

In the case of individual-wheel running gears with self-regulating,individually driven individual wheels, the influence of traction forceson the steering behavior may result in undesired travelling movement. Interms of production and heat, differential drive torques between thetraction motors cannot be avoided, and these torques result indifferential traction forces which may lead to undesired steering. Thesedifferential traction forces may also result from tolerance-dependent ortransverse-displacement-dependent changes in the radius of the rollingcircle of the driven individual wheels. Furthermore, with very smalltrack-curve radii and a large axle spacing, there is a reduction in thegauge of these individual wheels steered in such a manner.

If the wheel carriers, which can be rotated about a vertical pin, aremade to pivot by hydraulic actuating members, then a need for a notinconsiderable amount of space and high energy outlay should be expectedsince the wheel/rail contact forces which counteract the steeringmovement have to be overcome by the actuating members. When the vehicleis travelling through a curve, failure of a hydraulic actuating memberconstitutes a risk to travelling safety. If the influence of thetraction forces on the track guidance cannot be eliminated, then thehydraulic actuating members additionally have to compensatetraction-force differences.

SUMMARY OF THE INVENTION

The object of the invention is thus to provide a two-wheel running gearwhich has an individual-wheel drive for track-guided vehicles withcontrolled steering and, with minimal wear, high safety and low designoutlay, can both travel through narrow track curves and can also achieverelatively high speeds along a rectilinear track.

This object is achieved according to the invention by the featuresaccording to a two-wheeled running gear for track-guided vehicles,having a traction-assisted means for steering and having a wheelcarrier. The two wheels (4 and 4') on the common wheel carrier (3) arealigned parallel to one another on an (imaginary) connecting linebetween the individual-wheel axles, the connecting line beingperpendicular with respect to the wheel circumference, and are arrangedat a uniform spacing from one another. The wheel carrier (3) has twoalternatively usable, vertical pivot pins (2 and 2') which are locatedoutside the stand-up points of the wheels. A pivot pin (2, 2') isarranged on each side of the wheel carrier (3), and can be adjusted andarrested in the horizontal in dependence on the radius of the trackcurve. The wheel carrier (3) can be steered about a non-adjusted,arrested pivot pin (2 or 2'), which is located in a central position andis on the inside or outside of the curve. The invention thus avoids thedisadvantages mentioned above.

In contrast to the running gears which have been described from theprior art, the running gear which is designed according to the inventiondoes not have a central vertical pivot pin per wheel carrier with twoindividual wheels, but rather has two vertical pivot pins which arelocated outside the stand-up points of the wheels in each case. Inparticular, while the position of the pivot pin which is on the outsideof the curve at any one time is arrested, the wheel carrier is pivotedalternately about precisely this pin. The wheel carrier, with specificapplication of differential traction forces, is adjusted tangentiallywith respect to the rail and is retained at the desired steering angleby a separate arresting device. The desired steering angle isdetermined, for example, by a track-position measurement, and thedifferential traction forces are predetermined by an adjustment orregulating algorithm.

The pivot pins are actually formed by king pins. On the respectivesides, the wheel carrier is steered, in dependence on the track-curveradius, and with simultaneous arresting of the horizontal displacementmeans of the outer pivot pin, about the pivot pin. The pivot movementmay also be effected actively, for example by a pneumatic or hydraulicpivoting device or by the specific application of differential tractionforces, and, at the same time, be assisted by the wheel/rail contactforces. In the case of a track which has only shallow curvature or isrectilinear, the two pivot pins are arrested, as a result of which goodstability is achieved at relatively high speeds and the influence oftolerance-related traction-force differences is small or comparable withnon-steerable running gears. The steering and arresting operations areassisted by a convenient arrangement of the spring/damper combination,with the result that there is no danger of safety being put at risk inthe event of the traction motors failing.

The advantages which can be achieved by way of the invention consist, inparticular, in that the steering operation does not require anyactuating devices which consume additional energy; rather, thedifferential traction forces of the individual-wheel-drivenindividual-wheel running gear control the steering operation with lowenergy, as a natural actuating device, and are assisted by thewheel/rail contact forces in the process.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are described hereinbelow andillustrated in the drawing, in which:

FIG. 1 shows a plan view of the principle of the running gear;

FIG. 2 shows a plan view of the wheel carrier in its mounting;

FIG. 3A shows a front view of the wheel carrier;

FIG. 3B shows a detailed view of FIG. 3A.

FIG. 4 shows the arrangement of the spring/damper combination;

FIG. 5 shows a detail of the wheel carrier with spindle drive;

FIG. 6 shows a hydraulic actuating device; and

FIG. 7 shows a gear-wheel actuating device.

FIG. 8 shows the arrangement of a spring/damper combination providedwith changeable throttle cross-sections.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows the plan view of the principle of the running gear. Thedirection of movement of the running gear frame 1, which is illustratedwithout its leading part, is indicated by an arrow. The pivot pins (kingpins) 2 and 2' of the wheel carrier 3, which can be pivoted about thevertical, show that, in the vehicle position illustrated, rotation takesplace about the king pin on the outside of the curve. The actualsteering rolling radius is given by the spacing of the two pivot pins.Ideally, the individual wheels 4 and 4' are located in the track, i.e.the wheel axle is radial with respect to the present radius of curvatureand the wheel planes are located tangentially thereto. The reciprocalguidance of the wheel carrier 3 about the king pins 2 is effected by abearing segment ring, of which the running-gear-frame-mounted parts 5and 5' are illustrated in FIG. 1.

FIG. 2 shows a plan view of further details of the running gearprinciple. The springs 6 assume the task of suspending the running gearframe with respect to the vehicle body. On the respective sides, thewheel-carrier-mounted bearing segment rings 7 guide the pivot points 2with respect to the vehicle frame. One exemplary embodiment of thearresting device on the respective sides is equipped as a spring/dampercombination 8 with adjustable characteristic curves.

FIG. 3A illustrates the front view of the running gear principle. Inthis case, the running gear frame is configured as a so-called troughframe in order to permit a structure with a low-level carriage floor.The suspension of the vehicle body 9 is likewise illustrated in thefront view. The running-gear-frame-mounted bearing segment rings 5 areillustrated in section, as are the wheel-carrier-mounted bearing segmentring 7 and the corresponding guide of the king pin 2. The arrestingdevice 8 on the respective sides is indicated by the articulation point.A detailed view is illustrated in FIG. 3B.

FIGS. 4, 5, 6, 7 and 8 illustrate the various arresting and actuatingdevices in plan view. FIG. 4 shows the spring/damper combination 8, in aredundant arrangement of four, which influences the steering of wheelcarrier. FIG. 8 shows a single spring/damper combination with adjustablethrottle cross section 8.1 for selectively arresting pivot pins 2, 2'.

FIG. 5 illustrates the running gear in half-section with an exemplaryembodiment of the nut/spindle structure. This spindle 19 is articulatedon the king pin 2, and its nut 10 is articulated on the running gearframe 1 and driven by an electric motor 11.

An exemplary embodiment of the pneumatic or hydraulic actuating device12 is represented in FIG. 6. The actuating device is articulated on theking pin 2 and on the running gear frame 1.

FIG. 7 illustrates an exemplary embodiment of thegear-wheel/toothed-ring actuating device. The toothed ring 15 isfastened on the running gear frame 1, and the motor 14 is fastened onthe wheel carrier 3. Actuation of the wheel carrier is initiated in therunning gear frame via the gear wheel 13. A spring/damper combinationcan additionally assist the actuating operation.

What is claimed is:
 1. A two-wheeled running gear for a track-guidedvehicle comprising:a running gear frame having a first side and a secondside opposite the first side; a wheel carrier having a first side and asecond side opposite the first side; first and second wheels, the firstwheel coupled to the first side of the wheel carrier, the second wheelcoupled to the second side of the wheel carrier, each wheel having acenter and a circumference, the first and second wheels being alignedsubstantially parallel to one another on a line connecting the centersof the wheels and the circumferences of the wheels being substantiallyperpendicular to the line connecting the centers of the wheels, thefirst and second wheels being maintained at a substantially uniformdistance from one another; first and second vertical pivot pins, thefirst vertical pivot pin coupled to the first side of the wheel carrierand movably connected to the first side of the running gear frame, thesecond vertical pivot pin coupled to the second side of the wheelcarrier and movably connected to the second side of the running gearframe, the first and second wheels located between the first and secondvertical pins; and means for controlling a movement of the first pivotpin relative to the running gear frame such that, during a curved trackdrive, the first pivot pin is held substantially in place relative tothe running gear frame while the second pivot pin moves relative to therunning gear frame so that the line connecting the centers of the wheelsis maintained substantially parallel to the radius of curvature of thetrack.
 2. A running gear according to claim 1, further comprising:afirst circle-arc-shaped running gear section coupled to the first sideof the wheel carrier and to the first vertical pivot pin, the firstvertical pivot pin being movable along the first circle-arc-shapedrunning gear section; and a second circle-arc-shaped running gearsection coupled to the second side of the wheel carrier and to thesecond vertical pivot pin, the second vertical pivot pin being movablealong the second circle-arc-shaped running gear section.
 3. A runninggear according to claim 1, wherein the vertical pivot pins are formed byking pins.
 4. A running gear according to claim 2, wherein the means forcontrolling movement of the pivot pins further comprises at least one ofa first thrust-action spring element and a first guidance link coupledto the first side of the wheel carrier and for steering the wheelcarrier about a first virtual vertical pivot pin.
 5. A running gearaccording to claim 2, wherein the means for controlling movement of thepivot pins holds one of the vertical pivot pins at any desired positionalong its respective circle-arc-shaped running gear section, while theother vertical pin is maintained at a zero position along its respectivecircle-arc-shaped running gear section.
 6. A running gear according toclaim 1, wherein the wheel carrier is steered such that the wheels areat least one of steered and guided radially with respect to curvedtrack.
 7. A running gear according to claim 2, wherein the means forcontrolling movement of the pivot pins further comprises a firstchangeable throttle cross-section of a first spring/damper combinationcoupled to the first side of the wheel carrier and for arresting thefirst pivot vertical pin along the first circle-arc-shaped running gearsection by closing the first changeable throttle cross-section.
 8. Arunning gear according to claim 2, wherein the means for controllingmovement of the pivot pins further comprises one of a firstelectromagnetic and mechanical retaining device coupled to the firstside of the wheel carrier and for arresting the first pivot vertical pinalong the first circle-arc-shaped running gear section.
 9. A runninggear according to claim 2, wherein the means for controlling movement ofthe pivot pins further comprises a first nut/spindle structure driven bya first electric motor, coupled to the first side of the wheel carrier,and for arresting the first pivot vertical pin along the firstcircle-arc-shaped running gear section.
 10. A running gear according toclaim 2, wherein differential traction forces of the first wheeldisplace the first vertical pivot pin along the first circle-arc-shapedrunning gear section.
 11. A running gear according to claim 2, whereinthe means for controlling movement of the pivot pins further comprises:afirst pneumatic and/or hydraulic actuating device for displacing thefirst vertical pivot pin along the first circle-arc-shaped running gearsection.
 12. A running gear according to claim 2, wherein the means forcontrolling movement of the pivot pins further comprises a firstnut/spindle structure driven by a first electric motor for displacingthe first vertical pivot pin along the first circle-arc-shaped runninggear section.
 13. A running gear according to claim 2, wherein the meansfor controlling movement of the pivot pins further comprises a firsttoothed ring coupled to the first circle-arc-shaped running gear sectionand driven by at least one of a first electrically driven gear wheel anda first motor driven gear wheel, and for displacing the first verticalpivot pin along the first circle-arc-shaped running gear section.
 14. Arunning gear according to claim 1, wherein the wheel carrier is steeredabout the vertical pivot pin located exterior to a curvature of track.15. A running gear according to claim 1, wherein the wheel carrier issteered about the vertical pivot pin located interior to a curvature oftrack.
 16. A running gear according to claim 1, wherein the means forcontrolling further comprises a first arresting device connected to thefirst pivot pin and a second arresting device connected to the secondpin so that, on a straight track drive both pivot pins are locked inplace, and on a curved track drive one pivot pin is locked in placewhile the other pivot pin pivots in its guide in accordance with thecurvature of the track.
 17. A two-wheeled running gear for atrack-guided vehicle comprising:a running gear frame having a first sideand a second side opposite the first side; a wheel carrier having afirst side and a second side opposite the first side; first and secondwheels, the first wheel coupled to the first side of the wheel carrier,the second wheel coupled to the second side of the wheel carrier, eachwheel having a center and a circumference, the first and second wheelsbeing aligned substantially parallel to one another on a line connectingthe centers of the wheels and the circumferences of the wheelssubstantially perpendicular to the line connecting the centers of thewheels, the first and second wheels being maintained at a substantiallyuniform distance from one another; first and second vertical pivot pins,the first vertical pivot pin coupled to the first side of the wheelcarrier, the second vertical pivot pin coupled to the second side of thewheel carrier, the first and second wheels located between the first andsecond vertical pins; and means for selectively arresting individuallyand independently the first and second vertical pivot pins, said meansfor arresting coupled to the wheel carrier.